Thermoresponsive hollow magnetic microspheres with hyperthermia and controlled release properties

Thermoresponsive hollow magnetic microspheres consisting of a hollow magnetic core, a carbon shell, and a smart polymer layer are presented in this article. A carbon nanomaterial was used as a steric stabilizer for Fe₃O₄ nanoparticles and a supporter for polymer. The thermoresponsive monomer, N‐isopropyl acrylamide, was grafted on the carbon‐encapsulate hollows by surface radical polymerization. The experimental results indicate that the composites had a phase‐transition temperature around 43°C and a saturation magnetization of 56.9 emu/g; this showed apparent thermosensitivity and magnetism. The performances in hyperthermia evaluated by an inductive magnetic field showed that the hybrid microspheres had a specific absorption rate of 240 W/g. The model drug, 5‐fluorouracil, was loaded in and released from the microspheres with different release rates at 35 and 50°C. This demonstrated that the as‐synthesized microspheres had a thermotriggered release ability and would be a good drug carrier in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42617.     

Synthesis of cationic magnetite nanoparticles for intracellular protein delivery

Intracellular protein delivery shows great promise in the treatment of various diseases. However, therapeutic applications of this method are limited by its low delivery efficiency and poor targeting ability. As one of most important drug delivery cargoes, Fe₃O₄ nanoparticles (nFe₃O₄) have attracted much attention for both therapeutic and diagnostic applications, especially for targeting drug delivery. To use nFe₃O₄ for protein delivery, a simple but effective modification of nFe₃O₄ is critical to attach proteins on its surface. In this work, by designing and synthesizing cationic poly(2‐(dimethylamino)ethyl methacrylate) (PDMA)‐grafted nFe₃O₄ via in situ atom transfer radical polymerization (ATRP), we demonstrate a simple solution to improve interactions between nFe₃O₄ and proteins. With the grafted PDMA on the surface, nFe₃O₄ exhibits not only significant enhancement in dispersibility and stability in aqueous phase, but also an excellent capability to attach negative‐charged proteins. Moreover, with the assistance of external magnetic field, PDMA‐grafted nFe₃O₄ can be used as a targetable vector to deliver proteins into specific cells. This work provides a novel platform based on cationic magnetite nanoparticles that can deliver therapeutic proteins into specific sites for the treatment of various diseases. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40260.     

pH and magnetic field responsive protein-inorganic nanohybrid conjugated with biotin: A biocompatible carrier system targeting lung cancer cells

Multi-stimuli responsive carrier systems, specifically targeting tumor cells are of high significance to improve the efficacy of cancer chemotherapy. In the present study, we have developed, characterized, and biologically evaluated magnetic casein-calcium ferrite hybrid biopolymeric carrier conjugated with biotin for targeted delivery of cinnamaldehyde to lung carcinoma. The dual stimuli-responsive carrier was successfully synthesized with small size, good stability, and high drug encapsulation efficiency. Natural drug cinnamaldehyde was encapsulated in the hybrid carrier, on which biotin was conjugated to facilitate selective cellular uptake. The prepared drug-carrier system exhibited pH-responsive drug release behavior with a higher release rate under acidic conditions, which can be effectively applied in targeted cancer chemotherapy. The superparamagnetic nature of calcium ferrite enabled magnetically-modulated drug delivery with faster drug release, reaching 85.5% within 4 h, in response to magnetic field stimulus. Kinetic modeling of drug release projected the diffusion-controlled release mechanism. Cell viability assay performed on L929 fibroblast and A549 lung cancer cells verified the biocompatibility and cytotoxicity of the developed formulation, respectively. The nanohybrid carrier significantly increased the anticancer potential of cinnamaldehyde with an 18-fold reduction in the IC₅₀ value, signifying the biotin-functionalized protein-inorganic nanohybrid as an efficient multifunctional platform for targeted drug delivery.     

Encapsulation and release of cladribine from chitosan nanoparticles

This study shows the potential of chitosan (CH) nanoparticles as both an oral and IV drug delivery system using the anticancer drug cladribine as a model drug. Smooth, spherical nanoparticles were prepared by the ionotropic gelation of CH with sodium tripolyphosphate. Nanoparticle size depended on degree of hydration, drug loading, and crosslinking conditions, with the smallest nanoparticles in the size range of 212 ± 51 nm. Cladribine was entrapped in the CH matrix with an entrapment efficiency of up to 62%, depending on the initial loading. The release of cladribine followed a near‐Fickian diffusion rate over the first several hours and then reached a plateau. A second release phase began after 30–40 h of incubation in the release medium, and proceeded until ～100 h. Loaded CH nanoparticles that were crosslinked with genipin showed a delayed release profile, with only 40% of loaded drug being released after 100 h. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermoresponsive and magnetic molecularly imprinted polymers based on iron oxide encapsulated carbon nanotubes as a matrix for the selective adsorption and controlled release of 2,4,5‐trichlorophenol

Thermoresponsive and magnetic molecularly imprinted polymers (TMMIPs) based on magnetic carbon nanotubes (MCNTs) were prepared and applied to the switched recognition and controlled release of 2,4,5‐trichlorophenol (2,4,5‐TCP) from aqueous solution. In this study, MCNTs were first synthesized via the encapsulation of Fe₃O₄ nanoparticles into the tunnel of carbon nanotubes by a wet impregnation technology. Then, the TMMIPs were synthesized with N‐isopropyl acrylamide as a thermal functional monomer by free‐radical polymerization. The magnetic sensitivity and stability of the prepared materials were tested with a vibrating sample magnetometer (saturation magnetization = 1.4 emu/g) and atomic absorption spectrophotometer (in the pH range 3.0–8.0), respectively. The thermoresponsive properties of the TMMIPs were evaluated by two means, including the results of ultraviolet–visible spectroscopy and the controlled release of 2,4,5‐TCP at 30 and 40°C, respectively. The effects of the pH, initial concentration, and contact time on adsorption were examined with batch mode experiments, and several other compounds were selected as model analytes to evaluate the selective recognition performance of the TMMIPs. This demonstrated that the TMMIPs had a higher affinity for 2,4,5‐TCP than did the thermoresponsive and magnetic nonimprinted polymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42087.     

Controlled release of protein from core–shell nanofibers prepared by emulsion electrospinning based on green chemical

Direct application of active protein in practical food system suffers from the major disadvantage of protein inactivation caused by food components and environmental factors. This study is the first to encapsulate water‐soluble protein into hydrophobic polystyrene (PS) polymer via emulsion electrospinning technique based on green chemical L‐limonene to achieve sustained release of protein. Core–shell nanostructure with elongated domains was observed in electrospun fibers. In vitro release profiles suggest that a sustained release of protein was achieved. The increased release rate with PS molecular weight reveals that the release of protein could be well tuned by tailoring polymeric molecular weight, which is possibly attributed to the association of release rate with fiber inner structure and protein distribution in matrix. These results demonstrate that an excellent protein delivery system could be obtained via emulsion electrospinning based on green chemical for the application in antimicrobial packaging and filtration in food industry. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41811.     

Dual release kinetics of antimalarials from soy protein isolate‐carbopol‐polyacrylamide based hydrogels

The currently used antimalarials suffer from drug resistance which is hampering the global management of malaria infection. To overcome drug resistance, they are administered as combination therapies which involve combination of two or more antimalarials. In this study, chloroquine diphosphate and curcumin were encapsulated onto prepared soy protein isolate‐carbopol‐polyacrylamide based hydrogels. The hydrogels were pH sensitive and exhibited enhanced swelling capability at pH 7.4. The hydrogels were biodegradable which was observed by their SEM images after drug release. The release mechanisms of both drugs were influenced by the degree of crosslinking of the soy protein isolate in the hydrogel network and the presence of the other drug in the network. The release mechanisms of both drugs from the hydrogel networks followed super case transport II. These results suggested that the hydrogels were potential dual drug delivery systems for antimalarials whereby both drugs could work over different period of time and hence, have the potential to overcome drug resistance that is common with the presently used antimalarials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43918.     

PEGylation of MnO nanoparticles via catechol–Mn chelation to improving T1‐weighted magnetic resonance imaging application

To enhance biocompatibility and physiological stability of hydrophobic MnO nanoparticles as contrast agent of T₁‐weighted magnetic resonance imaging (MRI), dopamine‐functionalized poly(ethylene glycol) (PEG) was used to coat the surface of about 5 nm MnO nanoparticles. Although hydrophilic coating might decrease longitudinal relaxivity due to inhibiting the intimate contact between manganese of nanoparticle surface and proton in water molecules, higher longitudinal relaxivity was still maintained by manipulating the PEGylation degree of MnO nanoparticles. Moreover, in vivo MRI demonstrated considerable signal enhancement in liver and kidney using PEGylated MnO nanoparticles. Interestedly, the PEGylation induced the formation of about 120 nm clusters with high stability in storing and physiological conditions, indicating passive targeting potential to tumor and prolonged circulation in blood. In addition, the cytotoxicity of PEGylated MnO nanoparticles also proved negligible. Consequently, the convenient PEGylation strategy toward MnO nanoparticles could not only realize a good “trade‐off” between hydrophilic modification and high longitudinal relaxivity but also contribute additional advantages, such as passive targeting to tumor and long blood circulation, to MRI diagnosis of tumor. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42360.     

Synthesis,characterization, and properties of flexible magnetic nanocomposites of cobalt ferrite–polybenzoxazine–linear low‐density polyethylene

A simple method for the preparation of magnetic nanocomposites consisting of cobalt ferrite (CF; CoFe₂O₄) nanoparticles, polybenzoxazine (PB), linear low‐density polyethylene (LLDPE), and linear low‐density polyethylene‐g‐maleic anhydride (LgM) is described. The composites were prepared by the formation of benzoxazine (BA)–CF nanopowders followed by melt blending with LLDPE and the thermal curing of BA. The composites were characterized by X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, universal testing machine measurement, and vibrating sample magnetometry. The composites consisting of LLDPE, PB, and LgM (47.5L–47.5PB–5LgM) exhibited a higher tensile strength (23.82 MPa) than pure LLDPE and a greater elongation at break (6.11%) than pure PB. The tensile strength of the composites decreased from 19.92 to 18.55 MPa with increasing CF loading (from 14.25 to 33.25 wt %). The saturation magnetization of the composites containing 33.25 wt % CF was 18.28 emu/g, and it decreased with decreasing amount of CF in the composite. The composite films exhibited mechanical flexibility and magnetic properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization of novel quaternary chitosan derivative nanoparticles loaded with protein

The objective of this work was to characterize a novel quaternary chitosan derivative [O‐(2‐hydroxyl) propyl‐3‐trimethyl ammonium chitosan chloride (O‐HTCC)] nanoparticle system. O‐HTCC nanoparticles were prepared with a simple and mild ionic gelation method upon the addition of a sodium tripolyphosphate solution to a low‐molecular‐weight O‐HTCC solution. Highly cationic chitosan nanoparticles were prepared. Bovine serum albumin (BSA), a model protein drug, was incorporated into the nanoparticles. The physicochemical properties of the nanoparticles were determined with transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared analysis, differential scanning calorimetry, and X‐ray diffraction (XRD) patterns. The results showed that increasing the BSA concentration from 1.5 to 2.5 mg/mL promoted the BSA encapsulation efficiency from 57.3% to 87.5% and the loading capacity from 70.2% to 99.5%. Compared with the chitosan nanoparticles, the O‐HTCC nanoparticles had lower burst release. TEM revealed that the BSA‐loaded O‐HTCC nanoparticles were smaller than the O‐HTCC nanoparticles when the BSA concentration was 1.5 mg/mL; SEM showed that the size of the BSA‐loaded O‐HTCC nanoparticles was mostly affected by the BSA concentration, and the increase in size occurred with the concentration increasing. Thermograms and XRD of the BSA‐loaded nanoparticles suggested that polyelectrolyte–protein interactions increased with the BSA concentration increasing and greater chain realignment in the BSA‐loaded nanoparticles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

pH‐sensitive polyelectrolyte films derived from submicron chitosan/Eudragit® L 100‐55 complexes: Physicochemical characterization and in vitro drug release

The objectives of this study were to prepare films from submicron chitosan/Eudragit^® L100‐55 polyelectrolyte complexes (CH/EL PEC) and to assess the influence of CH molecular weight and CH/EL mass ratio on their structure and drug‐release properties. The films were obtained by a simple, environmentally friendly, casting/solvent evaporation method and the verapamil hydrochloride (VH) was used as model drug. Submicron size, narrow size distribution, and acceptable stability of CH/EL PECs were confirmed by DLS and laser Doppler microelectrophoresis. SEM analysis revealed nonporous inner structure and flat surface of the films. Interactions between comprising polymers and formation of CH/EL PEC were established by DSC and FT‐IR spectroscopy. In vitro swelling and drug release studies revealed the pH sensitivity of the films, with burst drug release in acidic conditions (pH 1.2) and sustained release in phosphate buffers pH 5.8, 6.8, and 7.4. The slowest VH release was achieved from the films prepared from equal amounts of EL and CH of higher molecular weight, confirming the significance of the CH/EL ratio and CH molecular weight on their ability to sustain drug release. The obtained results suggested that presented, simple, and eco‐friendly preparation procedure can be used to obtain pH‐sensitive CH/EL PEC films with a promising potential as drug carriers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42583.     

In vitro nifedipine release from poly(lactic acid)/chitosan nanoparticles loaded with nifedipine

In this study, nanoparticles based on poly(lactic acid) (PLA), chitosan (CS), and nifedipine (NIF) were prepared by an emulsion method with poly(ethylene oxide) (PEO) as an emulsifier. We investigated the most suitable conditions for preparing the poly(lactic acid)/chitosan/nifedipine nanoparticles (PCNs) by changing the distilled water volume, PEO content, and PLA/CS ratio. NIFs with different contents were loaded into poly(lactic acid)/chitosan nanoparticles (PCs) to study in vitro drug‐delivery systems. The PCNs were characterized with a Zetasizer particle size analyzer, field emission scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and X‐ray diffraction (XRD) methods. From the obtained results of the particle size parameters of the PCNs, the most suitable conditions for the preparation of the PCNs were found. The FTIR spectroscopy and XRD results show that NIF was loaded into the PCs. The PCNs had major basic particle sizes in the range 20–40 nm. NIF release from the PCNs was studied as a function of the pH of the immersed solution, the immersion time, and the NIF content. The kinetics of drug release were investigated and are reported to determine the type of release mechanism. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43330.     

“One‐pot” synthesis of well‐defined functional copolymer and its application as tumor‐targeting nanocarrier in drug delivery

A one‐pot synthesis is developed for PEG₆₀₀‐b‐poly(glycerol monoacrylate) (PEG₆₀₀‐b‐PGA), by which folate and superparamagnetic iron oxide nanoparticles (SPIONs) are assembled to form folic acid‐conjugated magnetic nanoparticles (FA‐MNPs) as a tumor targeting system. The synthesis consists of a “click” reaction and atom transfer radical polymerization (ATRP) to obtain the well‐defined furan‐protected maleimido‐terminated PEG₆₀₀‐b‐poly(solketal acrylate) (PEG₆₀₀‐b‐PSA) copolymer. After deprotection, the key copolymer N‐maleimido‐terminated PEG₆₀₀‐b‐PGA is successfully conjugated with thiol derivatives of folate and FITC, respectively. FA‐MNPs are developed by assembling of the resulting polymer FA‐PEG₆₀₀‐b‐PGA with SPIONs, and characterized for their size, surface charge, and superparamagnetic properties. To investigate the cellular uptake of the nanoparticles by Hela cells and φ2 cells using fluoresce technique, FA‐FITC‐MNPs are also obtained by assembling of FA‐PEG₆₀₀‐b‐PGA, FITC‐PEG₆₀₀‐b‐PGA with SPIONs. Qualitative and quantitative determinations of FA‐FITC‐MNPs show that the particles specifically internalized to Hela cells. No significant cytotoxicity is observed for these two kinds of cell lines. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40405.     

Study of a nanocomposite starch–clay for slow‐release of herbicides: Evidence of synergistic effects between the biodegradable matrix and exfoliated clay on herbicide release control

In this article a nanocomposite based on starch gel, a renewable polymer, and montmorillonite clay (MMT) is proposed as a host system for the slow‐delivery of a hydrophobic herbicide loaded in very high contents (50% in total weight), where the nanocomposite structure controls the release by imposing diffusional barriers to the active compound. The herbicide release rate in water showed that nanocomposites presented higher retentions than the neat samples (herbicide‐loaded starch or MMT), revealing a cooperative or synergic effect between the constituents. Biodegradation essays also revealed this cooperative behavior, showing longer biodegradation periods for the nanocomposite than the pristine materials. Also, a two‐step release was noticed, where the first step was controlled by starch (short periods) and the second was played by MMT (longer times). The nanocomposite structural analysis gave evidence that the release behavior is governed by the interaction between the constituents, even at very high herbicide contents. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41188.     

Composites of polymeric gels and magnetic nanoparticles: Preparation and drug release behavior

The article is concerned with the preparation of polymer–iron oxide nanocomposites and the study as drug‐delivery matrices under the influence of applied magnetic field. Biocompatible materials were prepared by incorporating an aqueous ferrofluid in poly(vinyl alcohol) and scleroglucan (SCL) hydrogels, loaded with theophylline as model drug for release studies. The in vitro release profile was obtained using a flat Franz cell and the kinetic parameters were derived applying a semiempirical power law. A magnetic characterization of nanoparticles contained in the ferrofluid was performed by obtaining the magnetization curve. For both systems, the observed drug release profiles decreased when a uniform external magnetic field is applied suggesting they can be used as environmental responsive matrices for biomedical applications. Dynamic rheological measurements show that a higher storage modulus and a more compact structure are obtained by incorporating the ferrofluid into the hydrogels. These rheological results and environmental electron scanning microscopy micrographs point to an understanding of release behavior once the magnetic field is applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity

A novel, bioadsorbent material of polyethylenimine‐modified magnetic chitosan microspheres enwrapping magnetic silica nanoparticles (Fe₃O₄–SiO₂–CTS‐PEI) was prepared under relatively mild conditions. The characterization results indicated that the adsorbent exhibited high acid resistance and magnetic responsiveness. The Fe₃O₄ loss of the adsorbent was measured as 0.09% after immersion in pH 2.0 water for 24 h, and the saturated magnetization was 11.7 emu/g. The introduction of PEI obviously improved the adsorption capacity of Cr(VI) onto the adsorbent by approximately 2.5 times. The adsorption isotherms and kinetics preferably fit the Langmuir model and the pseudo‐second‐order model. The maximum adsorption capacity was determined as 236.4 mg/g at 25°C, which was much improved compared to other magnetic chitosan materials, and the equilibrium was reached within 60 to 120 min. The obtained thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. Furthermore, the Cr(VI)‐adsorbed adsorbent could be effectively regenerated using a 0.1 mol/L NaOH solution, and the adsorbent showed a good reusability. Due to the properties of good acid resistance, strong magnetic responsiveness, high adsorption capacity, and relatively rapid adsorption rate, the Fe₃O₄–SiO₂–CTS‐PEI microspheres have a potential use in Cr(VI) removal from acidic wastewater. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43078.     

Synthesis,antimicrobial, and release behaviors of tetracycline hydrochloride loaded poly (VInyl alcohol)/chitosan/ZrO2 nanofibers

Tetracycline hydrochloride loaded poly (vinyl alcohol)/chitosan/ZrO₂ (Tet‐PVA/CS/ZrO₂) hybrid nanofibers were fabricated via electrospinning technique. The representative weight ratio of PVA/CS at 3 : 1 was chosen to fabricate drug carrier PVA/CS/ZrO₂ nanofibers. The drug carrier showed a decrease in average diameter with the increase of ZrO₂ content at given conditions, and the nanofibers were uneven and interspersed with spindle‐shape beads with ZrO₂ content at 60 wt % and above. The networks linked by hydrogen and Zr–O–C bonds among PVA, CS, and ZrO₂ units resulted in the improving of thermal stability and decreasing of crystallinity of the polymeric matrix. Moreover, the incorporation of ZrO₂ endowed the fibers with ultraviolet shielding effect ranged from 200 to 400 nm. The Tet loading dosage had no obvious effect on the morphology and size of the medicated nanofibers at Tet content below 8 wt %, but interspersed with spindle‐shaped beads when Tet content increased to 10 wt %. The Tet‐PVA/CS/ZrO₂) nanofibers showed well controlled release and better antimicrobial activity against Staphylococcus aureus, and the Tet release from the medicated nanofibers could be described by Fickian diffusion model for M_t /M_∞< 0.6. These medicated nanofibers may have potential as a suitable material in drug delivery and wound dressing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42506.     

Properties of insulin–chitosan complexes obtained by an alkylation reaction on chitosan

In this study, we investigated the influence of hydrophobized chitosan on the formation and thermodynamic and surface tension properties of insulin–chitosan (I–Ch) polyelectrolyte complexes (PECs). We used an alkylation procedure to insert 12 carbon chains along the chitosan macromolecule with final substitution degrees of 5, 10, and 50%. NMR and IR spectroscopy were used to evaluate the success and extent of the hydrophobization procedure. Isothermal titration calorimetry (ITC) was used to determine the type and extent of the existing intermolecular interactions between the different constituting components of the insulin–hydrophobized chitosan PECs. Through the surface tension and diffusion coefficients at the air–water interface and ITC experiments with different I–Ch proportions, we demonstrated that around 34, 24, 25, and 60–80 insulin molecules saturated 0, 5, 10, and 50% hydrophobized chitosans, respectively. Surface tension experiments at the air–water interface demonstrated that the interaction of insulin molecules on the unmodified chitosan increased the hydrophobicity; this was mainly due to electrostatic interaction. On the contrary, insulin–hydrophobized chitosan interaction lowered the PEC hydrophobicity because of insulin alkyl chain interaction, and therefore, the hydrophilic insulin groups at the PEC surface contributed to a higher surface tension. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39999.     

Interforce initiated by magnetic nanoparticles for reducing internal concentration polarization in CTA forward osmosis membrane

The interforce between the magnetic composite forward osmosis (FO) membranes and the magnetic draw solution was proposed to reduce the internal concentration polarization (ICP) of FO process, and realized the synergetic permeability improvement of resultant FO membranes. The key factor was the successful fabrication of the Fe₃O₄ magnetic nanoparticles (MNPs) with small‐size and narrow distribution via co‐precipitation method. The cellulose triacetate (CTA) magnetic composite FO membranes were fabricated using Fe₃O₄ as additive via in situ interfacial polymerization, and named CTA‐Fe₃O₄. Dynamic light scattering (DLS) and zeta results showed that the coated sodium oleate on the MNPs explained their reducing aggregation and the stability of various pHs. The MNPs' surface segregation during demixing process resulted in the improvement of hydrophilicity, Fe content and roughness of resultant CTA‐Fe₃O₄ composite FO membranes. Furthermore, the in situ interfacial polymerization resulted in the formation of the polyamide selective layer, and the CTA‐Fe₃O₄ membrane's N content was 11.02% to 11.12%. The permeability properties (FO and pressure retarded osmosis modules) were characterized using 1.0M NaCl and 100 mg/L Fe₃O₄ as draw solutions, respectively. The results indicated that the higher concentration of MNPs supplied more interforce and better FO permeability properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44852.     

Controlled co‐delivery of hydrophilic and hydrophobic drugs from thermosensitive and crystallizable copolymer nanoparticles

Functionalized amphiphilic block copolymers poly(N‐isopropyl acrylamide)‐b‐poly(stearyl methacrylate) (PNIPAM‐PSMA) are synthesized. Their self‐assembled core‐shell nanoparticles have the hydrophilic thermosensitive shell and hydrophobic crystallizable core. Nanoparticles exhibit volume phase transition at temperature of 38 °C and its poly(stearyl methacrylate) (PSMA) moiety could form nano size crystals to retain drugs, making them good carriers for drug co‐delivery system. Thermosensitivity and crystallinity of nanoparticles are characterized with dynamic light scattering (DLS), differential scanning calorimetry (DSC), small‐angle X‐ray scattering (SAXS), and atomic force microscopy (AFM). The interactions and relationship between chemical structures of copolymer nanoparticles and loading drugs are discussed. Different loading techniques and combined loading of hydrophobic/hydrophilic drugs are studied. Nanoparticles show a good and controllable drug loading capacity (DL) of hydrophilic/hydrophobic drugs. The drugs release kinetics is analyzed with Fick's law and Weibull model. A general method for analyzing drug release kinetics from nanoparticles is proposed. Weibull model is well fitted and the parameters with definite physical meaning are analyzed. PNIPAM‐PSMA nanoparticles show a quite different thermal response, temporal regulation, and sustained release effect of hydrophilic and hydrophobic drugs, suggesting a promising application in extended and controlled co‐delivery system of multi‐drug. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44132.